Trump is incapable of disavowing such statements or effectively
changing the subject. Instead, he doubles down.

By aggressively pushing back, interrupting and correcting when
Trump is in the wrong, Clinton can rattle and annoy
him, drawing out responses that escalate in both anger and
stupidity.

Consider, for example, Trump's Miss Teen South Carolina-level word salad when
pressed on whether he really has a plan to beat ISIS, a
line of questioning that somehow led Trump into saying
he'll probably replace much of the career leadership of the
military soon after entering office:

LAUER: But yesterday, you actually told us a little bit about
your plan in your speech. You said this. Quote, "We're going to
convene my top generals and they will have 30 days to submit a
plan for soundly and quickly defeating ISIS." So is the plan
you've been hiding this whole time asking someone else for their
plan?

TRUMP: No. But when I do come up with a plan that I like and that
perhaps agrees with mine, or maybe doesn't — I may love what the
generals come back with. I will convene ...

LAUER: But you have your own plan?

TRUMP: I have a plan. But I want to be — I don't want to — look.
I have a very substantial chance of winning. Make America great
again. We're going to make America great again. I have a
substantial chance of winning. If I win, I don't want to
broadcast to the enemy exactly what my plan is.

LAUER: But you're going to ...

TRUMP: And let me tell you, if I like maybe a combination of my
plan and the generals' plan, or the generals' plan, if I like
their plan, Matt, I'm not going to call you up and say, "Matt, we
have a great plan." This is what Obama does. "We're going to
leave Iraq on a certain day."

LAUER: But you're going to convene a panel of generals, and
you've already said you know more about ISIS than those generals
do.

TRUMP: Well, they'll probably be different generals, to be honest
with you.

Or consider his response to a questioning about his past praise
of Putin.

Say he'll say nice
things about Putin as long as Putin says nice things about
him.

Call Putin "very much of
a leader" with "very strong control over his country" (in which
he has decimated the independent press and allegedly had
political opponents assassinated).

Say Putin has been a
far stronger leader than Barack Obama.

In both of these series of questions, Trump got more rattled,
more adamant, and more bizarre as the questioning went on. And
that was just under aggressive questioning by an
interviewer. Imagine how he's likely to react under pressure from
a political opponent.

U.S.
Democratic presidential nominee Hillary Clinton arrives at the
airport following a campaign Voter Registration Rally at the
University of South Florida in Tampa, Florida, United States,
September 6, 2016.Reuters/Brian
Snyder

Remember, during the primaries, Trump allowed himself to get
baited in to bragging about the size of his penis on a debate
stage. This is not a man with discretion or self-control.

When I tweeted that Wednesday's forum showed Clinton should be as
aggressive as possible when debating Trump, my MSNBC colleague
Irin Carmon responded
that this is a risky strategy for a female candidate.

Ordinarily, I would say that's true. But Trump's response to
Clinton's aggression is likely to be be so overaggressive and
undirected as to make her focused aggression seem measured
and presidential. Plus, aggression from Clinton will help to
combat Trump's charges that she lacks the "strength and stamina"
to be president.

Clinton's team has already been sending signals about their
intention to rattle Trump in the debates. Now we know it
shouldn't be too hard for her to do so.

*Disclosure: In addition to my duties at Business Insider, I
am a contributor to MSNBC, but I was not involved in the
production of the forum.

This is a column. The opinions and conclusions expressed above are those of the author.